Acceleration of FGMRES using fast multipole method for method of moments based on combined tangential formulation

In this study, we demonstrate an acceleration of flexible generalized minimal residual algorithm (FGMRES)[1] implemented with the method of moments and the fast multipole method (FMM), based on a combined tangential formulation. For the implementation of the FGMRES incorporated with the FMM concept, we propose a new definition of the truncation number for the FMM operator within the inner solver. The proposed truncation number provides an optimal variable preconditioner by controlling the accuracy and computational cost of the inner iteration.